The Bluetooth standard (“Bluetooth”) is a wireless technology standard for exchanging data over short distances (using short-wavelength ultra-high frequency radio waves in the ISM radio band ranging from 2.4 to 2.485 GHz) from fixed and mobile devices, and building personal area networks (“PANs”). The Bluetooth standard is a wire-replacement communications protocol primarily designed for low-power consumption, with a short range based on relatively low-cost transceiver microchips. Because the devices use a radio (broadcast) communications system, they do not have to be in visual line of sight of each other. The effective range of communication between Bluetooth devices varies due to propagation conditions, material coverage, production sample variations, antenna configurations and battery conditions. Other versions include Bluetooth Low Energy (“Bluetooth LE”), which is a wireless personal area network technology designed and marketed by the Bluetooth Special Interest Group aimed at applications in the healthcare, fitness, beacons, security, and home entertainment industries. Compared to Classic Bluetooth, Bluetooth LE is intended to provide considerably reduced power consumption and cost while maintaining a similar communication range.
Bluetooth uses a packet-based protocol with a master-slave structure. A master device may be in data communication with a plurality of slave devices, forming a piconet. All devices in a piconet share the master device's clock.
A Bluetooth device in discoverable mode transmits the following information on demand: device name, device class, list of services, and technical information such as device features, manufacturer, Bluetooth specification used, clock offset, and the like.
Any device may perform an inquiry to find other devices to connect to, and any device can be configured to respond to such inquiries. Every Bluetooth device has a unique 48-bit identifying address.
For security reasons, a device with hardware and software that implement the Bluetooth standard (a “Bluetooth device”) is provided with selective control over which other remote Bluetooth devices can connect to it. At the same time, it is useful for Bluetooth devices to be able to establish a connection with other Bluetooth devices without user intervention (for example, as soon as the devices are in range of each other).
To resolve these competing priorities, Bluetooth uses a process called device pairing to create bonds between devices. The pairing process may either be triggered either by an explicit request to generate a bond (for example, a user of a device requests to “Add a Bluetooth device”) or be triggered automatically when connecting to a new device where the identity of the new device is required for security purposes. When pairing successfully completes, a bond forms between the two devices, enabling those two devices to connect to each other in the future without repeating the pairing process to confirm device identities.
During pairing, the two Bluetooth devices may establish a relationship by creating a shared link key. If both devices store the same link key, they are said to be paired or bonded. A device that wants to communicate only with a bonded device can cryptographically authenticate the identity of the other device, ensuring it is the same device it previously paired with. Once a link key is generated, an authenticated asynchronous connectionless link between the devices may be encrypted to protect exchanged data against eavesdropping.
Bluetooth devices may be used to implement device location tracking within a defined area, for example by deploying a plurality of Bluetooth devices in known fixed locations in the defined area and providing one or more mobile Bluetooth devices to the people or equipment to be tracked. The mobile Bluetooth devices may be set to automatically connect with the fixed Bluetooth devices, making it possible to determine the location of the mobile Bluetooth device based on which fixed Bluetooth device(s) it is connected to.
Conventional Bluetooth device implementations of local location tracking may not be scalable to practical commercial deployments due to the potential of excessive power consumption on the part of the mobile devices and “connectorial explosion” problems (analogous to the combinatorial explosion problem, but refers to exponential increases in connections) on the part of the fixed devices.